Active casing treatment adapted with movable sleeve

ABSTRACT

Methods and systems are provided for a compressor adapted with a movable sleeve and an active casing treatment that form separate air flow chambers. In one example, a method includes flowing intake air in a first direction through a casing to an impeller of a compressor, selectively flowing intake air from the casing through a first chamber in an opposite, second direction, the first chamber circumferentially surrounding the casing, and selectively flowing intake air in the first direction through a second chamber to the impeller, the second chamber circumferentially surrounding the first chamber. In this way, compressor surge may be mitigated without reducing compressor efficiency at higher air flow rates.

FIELD

The present description relates generally to methods and systems forcontrolling a vehicle engine to reduce noise emitted during surgerecirculation flow.

BACKGROUND/SUMMARY

By incorporating a turbocharger into an engine of a vehicle, theefficiency and power output of the engine may be improved. The forcedinduction of extra air into a combustion chamber of the engineproportionally induces the combustion of additional fuel, therebyproducing more power than obtained from air intake at ambient pressure.The turbocharger may include an exhaust driven turbine coupled to acompressor via a drive shaft. The compressor may be fluidly coupled toan air intake manifold in the engine connected to a plurality of enginecylinders which, during combustion, produces exhaust gas that may bedirected to a turbine wheel, driving the rotation of the turbine and, inturn, the rotation of the compressor. The use of a compressor allows asmaller displacement engine to provide as much power as a largerdisplacement engine, but with additional fuel economy benefits.

However, compressors are prone to surge and choke. For example, when anoperator tips-out of an accelerator pedal, air flow decreases, leadingto reduced forward flow through the compressor at high pressure ratio(PR), possibly leading to compressor surge. In another example, surgemay be caused in part by high levels of cooled exhaust gas recirculation(EGR) which increase compressor pressure while decreasing mass flowthrough the compressor. Compressor surge can lead to NVH issues such asundesirable noise from the engine intake system.

Compressor choke may be encountered at high flows, when an increase incompressor speed gives a diminishing increase in the rate of flow. Whenthe flow at any point in the compressor reaches the choke condition, nofurther flow rate increase is possible. This condition represents themaximum compressor volumetric flow rate as a function of the pressureratio. Choke occurs when the air flow mass through the compressor cannotbe increased for a given speed of the compressor. The flow rate into thecompressor may be limited by the size of the compressor inlet, and whenthe flow at the inlet reaches sonic velocity, the flow may not beincreased further. As one example, choke may occur when an operatortips-in from a part load or idle conditions to a high load condition,such as when going uphill with a load.

Various approaches have been developed to address the issue ofcompressor inefficiency leading to surge including providing arecirculation pathway for gas flow. One example approach is shown byHomer et al. in U.S. Pat. No. 6,648,594 B1. Therein, a compressorhousing forming an active casing treatment having a plurality of bypasschannels, acting as short cuts for air flow, is disclosed. The channelsare fluidly connected to an air intake gallery separated from the mainair inlet of the compressor by the compressor housing. Air flow throughthe channels is controlled by a slidable or rotatable sleeve. To reducecompressor surge, the sleeve may be adjusted to open a slot that allowsrecirculation through the air intake gallery to flow air from thecompressor wheel to the compressor inlet. At high engine speeds,additional air may enter the compressor through the air intake galleryto reach the compressor wheel, thereby preventing engine choke.

However, the inventors herein have recognized potential issues with suchsystems. As one example, undesirable noise arising from oscillations ofair flow may occur during light engine loads near the surge limit. Thenoise may be suppressed by providing a recirculation path in the activecasing treatment adapted with dampening elements such as deflectors orbaffles. The incorporation of such structures in the recirculation path,however, hinders air flow during high engine operating loads near or ina choke region of compressor operation. High volume air flow through theflow path in an opposite direction from surge recirculation flow isdesirable for preventing turbocharger choke but the presence of noisesuppressing elements may restrict flow so that the response of theactive casing treatment to avoid conditions leading to compressor chokeis less efficient.

Another potential issue with active casing treatments as described abovearises from instances where the movable sleeve may become stuck. Overtime, particulates and other matter may infiltrate the space between themovable sleeve and compressor casing resulting in the binding of thesleeve to the casing and hindering the operation of the sleeve. This mayresult in unstable operation of the compressor, and, depending on theposition in which the sleeve is immobilized, may increase the likelihoodof turbocharger surge or choke.

In one example, the issues described above may be addressed by a methodincluding flowing intake air in a first direction through a casing to animpeller of a compressor, selectively flowing intake air from the casingthrough a first chamber in an opposite, second direction, the firstchamber circumferentially surrounding the casing, and selectivelyflowing intake air in the first direction through a second chamber tothe impeller, the second chamber circumferentially surrounding the firstchamber. In this way, noise produced during low engine speeds and lightengine loads may be minimized without adversely affecting high volumeflow during heavy engine loads.

As one example, an active casing treatment for a compressor inlet isconfigured with a movable sleeve. By sliding the sleeve axially along acompressor casing in which the active casing treatment is arranged, thesleeve may alternate between opening a bleed port while closing aninjection port of the active casing treatment, or closing the bleed portwhile opening the injection port. The bleed port includes an opening toa first chamber arranged between the compressor casing and the movablesleeve while the injection port includes an opening to a second chamberdisposed between the movable sleeve and the compressor housing. Thebleed port fluidly couples the first chamber to an inner passage of airflow through the compressor inlet. Similarly, the injection port fluidlycouples the second chamber to the inner passage of the compressor inlet.The first chamber may include noise deflectors or baffles to mitigatenoise due to surge flow, while such structures may not be present in thesecond chamber.

The movement of the sleeve is controlled by an actuating mechanism thatshifts the sleeve axially, to adjust flow between the bleed port andinjection port. The mechanism may also move the sleeve rotationally toprevent binding of the sleeve to the compressor casing. The actuatingmechanism may be configured with a linkage that enables the motor of theactuating mechanism to be positioned external to the compressor housingwhile still engaging the movement of the movable sleeve. The motion ofthe linkage, as controlled by the motor, is translated into theadjustment of the movable sleeve with respect to the positions of thebleed port and the injection port.

In this way, by providing separate circulation pathways for compressoroperation outside of surge and choke limits, unwanted noise during lightengine operations may be effectively dampened without loweringcompressor efficiency during higher end engine operations. Adhering ofthe sleeve to the compressor casing is prevented by minimizing theinterfacing contact surface to that formed by 3 or more ribs spacedcircumferentially around the casing and the continuous surface at theend that covers the ports. The axial contact length of the ribs providesstability to prevent the sleeve from misaligning on the casing andbecoming bound up. The relatively small contact area inhibits theaccumulation of matter between the sleeve and the casing. The technicaleffect of configuring an active casing treatment with separate surge andchoke circulation paths is that extension of surge and choke limits ismaintained while additional features of the active casing treatment areincluded, such as noise suppression.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example engine system for a vehicle.

FIG. 2A shows a cut-out view of a compressor inlet with an active casingtreatment and movable sleeve with a bleed port open to flow.

FIG. 2B shows a cut-out view of a compressor inlet with an active casingtreatment and movable sleeve with an injection port open to flow.

FIG. 3 shows an isometric perspective view of a compressor inlet with amovable sleeve connected to a rotary actuator.

FIG. 4A shows a side view of a movable sleeve connected to a linkage ofa rotary actuator, in a first position.

FIG. 4B shows a side view of a movable sleeve connected to linkage of arotary actuator, in a second position.

FIG. 5 shows a front view of a compressor inlet with a movable sleeveconnected to a first branch of a linkage of a rotary actuator.

FIG. 6A shows a schematic illustration of a movable sleeve connected toa rotary actuator via a linkage, in a first position.

FIG. 6B shows a schematic illustration of a movable sleeve connected toa rotary actuator via a linkage, in a second position.

FIG. 7A shows a schematic illustration of a movable sleeve connected toa linear actuator via a linkage, in a first position.

FIG. 7B shows a schematic illustration of a movable sleeve connected toa linear actuator via a linkage, in a second position.

FIG. 8 depicts a flow chart of an example method for operation of anactive casing treatment coupled with a movable sleeve.

FIG. 9 shows an example compressor map.

FIGS. 2-4B are shown approximately to scale.

DETAILED DESCRIPTION

The following description relates to systems and methods for controllingoperation of a turbocharger compressor's active casing treatment toreduce surge and choke occurrence. One non-limiting embodiment of ahybrid vehicle system including a turbocharged engine is shown inFIG. 1. The turbocharged engine may utilize an exhaust turbine-drivencompressor that may be positioned in an intake passage of the engine.The compressor may include an outer housing with an inlet conduit (e.g.,intake passage) enclosing a casing and an impeller (e.g., compressorwheel) disposed at a downstream end of the casing, as illustrated inFIGS. 2A-2B. The impeller may include one or more blades and isrotatable about a central axis of the compressor. The compressor may beadapted with an active casing treatment including a plurality of portsdisposed in a wall of the casing providing alternate pathways for aircirculation to avoid compressor surge and choke. A movable sleeve,configured to slide axially to align with each of the plurality ofports, may circumferentially surround the casing disposed in the inletconduit. A first chamber, coupled to a bleed port of the active casingtreatment, is arranged between an inner surface of the movable sleeveand an outer surface of the compressor casing and may constitute a firstcirculation path for air recirculation during light engine loads. Asecond chamber, coupled to an injection port of the active casingtreatment, may be formed between an outer surface of the movable sleeveand an inner surface of the compressor housing, acting as a secondcirculation pathway for injection of air to an outlet end of thecompressor during high engine loads. The sliding of the movable sleevemay be controlled by an actuating mechanism shown in FIG. 3 thatincludes a connecting element, or linkage, that drives an axial androtational movement of the movable sleeve. The pivoting of the linkage,translated into the axial and rotational sliding of the movable sleeve,is depicted in FIGS. 4A and 4B. The attachment of the linkage, relativeto a central axis of the compressor, to an outer surface of the moveablesleeve is shown in FIG. 5 from a front view. The adjustment of themoveable sleeve as performed by a rotary actuator between a firstposition and a second position is shown in FIGS. 6A-6B. A linearactuator may similarly slide the moveable sleeve between the first andsecond position, as depicted in FIGS. 7A-7B. As shown in FIG. 8, thepositioning of the movable sleeve with respect to the plurality of portsmay be controlled based on compressor surge and choke conditions, forexample according to a compressor map shown in FIG. 9. In this way, anactive casing treatment adapted with a movable sleeve may be used toreduce unwanted noise during light engine loads in addition tocircumventing engine surge and choke.

Compressor operator limits will be referred to throughout the followingdetailed descriptions and may be clarified in conjunction with acompressor map illustrated in FIG. 9 showing flow rate through thecompressor as a function of a pressure ratio across the compressor. Asurge limit delineates a lower limit air flow for compressor operationwhile a choke limit defines an upper limit air flow. For example, dashedline 902 represents a lower limit boundary that is the surge limit andan upper limit boundary, indicated by dashed line 904, represents thechoke limit. Compressor surge may occur during low compressor flowconditions, such as rapid engine unloading events, during which theturbine continues to spin at a relatively high speed, pressurizing theair downstream of the compressor. This leads to a high pressure zone atthe outlet of the compressor, driving a reversal in the air flowdirection that may cause degradation of the turbocharger. Compressoroperating efficiency—as depicted by the curved lines marked withpercentages—reduces as the operating point nears the surge limit.Operating in the region to the left of dashed line 902 may (e.g., withrelatively low compressor mass flow and mid-to-high pressure ratio)result in compressor surge and even lower efficiency. Moving the surgeline to the left can increase the compressor operating efficiency of agiven operating point.

Operation beyond the upper limiting boundary of compressor pressureratio relative to mass flow (e.g. in a region to the right of dashedline 904 defined by relatively high compressor mass flow and relativelylow pressure ratio) results in turbocharger choke. Choke may occurduring transient over speed events where, for example, an increase inengine load subjects the turbocharger to flow beyond the tolerance ofthe turbocharger. The rotational speed of the turbine driving thecompressor may be higher than the maximum design speed of the turbo.Repeated instances of turbocharger choke may also cause degradation ofthe turbocharger and/or limit engine torque.

Turning now to FIG. 1, an example of a cylinder 14 of an internalcombustion engine 10 is illustrated, which may be included in a vehicle5. Engine 10 may be controlled at least partially by a control system,including a controller 12, and by input from a vehicle operator 130 viaan input device 132. In this example, input device 132 includes anaccelerator pedal and a pedal position sensor 134 for generating aproportional pedal position signal PP. Cylinder (herein, also“combustion chamber”) 14 of engine 10 may include combustion chamberwalls 136 with a piston 138 positioned therein. Piston 138 may becoupled to a crankshaft 140 so that reciprocating motion of the pistonis translated into rotational motion of the crankshaft. Crankshaft 140may be coupled to at least one drive wheel 55 of the passenger vehiclevia a transmission 54, as described further below. Further, a startermotor (not shown) may be coupled to crankshaft 140 via a flywheel toenable a starting operation of engine 10.

In some examples, vehicle 5 may be a hybrid vehicle with multiplesources of torque available to one or more vehicle wheels 55. In otherexamples, vehicle 5 is a conventional vehicle with only an engine. Inthe example shown, vehicle 5 includes engine 10 and an electric machine52. Electric machine 52 may be a motor or a motor/generator. Crankshaft140 of engine 10 and electric machine 52 are connected via transmission54 to vehicle wheels 55 when one or more clutches 56 are engaged. In thedepicted example, a first clutch 56 is provided between crankshaft 140and electric machine 52, and a second clutch 56 is provided betweenelectric machine 52 and transmission 54. Controller 12 may send a signalto an actuator of each clutch 56 to engage or disengage the clutch, soas to connect or disconnect crankshaft 140 from electric machine 52 andthe components connected thereto, and/or connect or disconnect electricmachine 52 from transmission 54 and the components connected thereto.Transmission 54 may be a gearbox, a planetary gear system, or anothertype of transmission. The powertrain may be configured in variousmanners including as a parallel, a series, or a series-parallel hybridvehicle.

Electric machine 52 receives electrical power from a traction battery 58to provide torque to vehicle wheels 55. Electric machine 52 may also beoperated as a generator to provide electrical power to charge battery58, for example, during a braking operation.

Cylinder 14 of engine 10 can receive intake air via a series of intakeair passages 142, 144, and 146. Intake air passage 146 can communicatewith other cylinders of engine 10 in addition to cylinder 14. In someexamples, one or more of the intake passages may include a boostingdevice, such as a turbocharger or a supercharger. For example, FIG. 1shows engine 10 configured with a turbocharger, including a compressor174 arranged between intake passages 142 and 144 and an exhaust turbine176 arranged along an exhaust passage 148. Compressor 174 may be atleast partially powered by exhaust turbine 176 via a shaft 180 when theboosting device is configured as a turbocharger. However, in otherexamples, such as when engine 10 is provided with a supercharger,compressor 174 may be powered by mechanical input from a motor or theengine and exhaust turbine 176 may be optionally omitted.

A throttle 162 including a throttle plate 164 may be provided in theengine intake passages for varying the flow rate and/or pressure ofintake air provided to the engine cylinders. For example, throttle 162may be positioned downstream of compressor 174, as shown in FIG. 1, ormay be alternatively provided upstream of compressor 174.

Exhaust passage 148 can receive exhaust gases from other cylinders ofengine 10 in addition to cylinder 14. An exhaust gas sensor 128 is showncoupled to exhaust passage 148 upstream of an emission control device178. Exhaust gas sensor 128 may be selected from among various suitablesensors for providing an indication of exhaust gas air/fuel ratio (AFR),such as a linear oxygen sensor or UEGO (universal or wide-range exhaustgas oxygen), a two-state oxygen sensor or EGO (as depicted), a HEGO(heated EGO), a NOx, a HC, or a CO sensor, for example. Emission controldevice 178 may be a three-way catalyst, a NOx trap, various otheremission control devices, or combinations thereof.

Each cylinder of engine 10 may include one or more intake valves and oneor more exhaust valves. For example, cylinder 14 is shown including atleast one intake poppet valve 150 and at least one exhaust poppet valve156 located at an upper region of cylinder 14. In some examples, eachcylinder of engine 10, including cylinder 14, may include at least twointake poppet valves and at least two exhaust poppet valves located atan upper region of the cylinder. Intake valve 150 may be controlled bycontroller 12 via an actuator 152. Similarly, exhaust valve 156 may becontrolled by controller 12 via an actuator 154. The positions of intakevalve 150 and exhaust valve 156 may be determined by respective valveposition sensors (not shown).

During some conditions, controller 12 may vary the signals provided toactuators 152 and 154 to control the opening and closing of therespective intake and exhaust valves. The valve actuators may be of anelectric valve actuation type, a cam actuation type, or a combinationthereof. The intake and exhaust valve timing may be controlledconcurrently, or any of a possibility of variable intake cam timing,variable exhaust cam timing, dual independent variable cam timing, orfixed cam timing may be used. Each cam actuation system may include oneor more cams and may utilize one or more of cam profile switching (CPS),variable cam timing (VCT), variable valve timing (VVT), and/or variablevalve lift (VVL) systems that may be operated by controller 12 to varyvalve operation. For example, cylinder 14 may alternatively include anintake valve controlled via electric valve actuation and an exhaustvalve controlled via cam actuation, including CPS and/or VCT. In otherexamples, the intake and exhaust valves may be controlled by a commonvalve actuator (or actuation system) or a variable valve timing actuator(or actuation system).

Cylinder 14 can have a compression ratio, which is a ratio of volumeswhen piston 138 is at bottom dead center (BDC) to top dead center (TDC).In one example, the compression ratio is in the range of 9:1 to 10:1.However, in some examples where different fuels are used, thecompression ratio may be increased. This may happen, for example, whenhigher octane fuels or fuels with higher latent enthalpy of vaporizationare used. The compression ratio may also be increased if directinjection is used due to its effect on engine knock.

In some examples, each cylinder of engine 10 may include a spark plug192 for initiating combustion. An ignition system 190 can provide anignition spark to combustion chamber 14 via spark plug 192 in responseto a spark advance signal SA from controller 12, under select operatingmodes. A timing of signal SA may be adjusted based on engine operatingconditions and driver torque demand. For example, spark may be providedat maximum brake torque (MBT) timing to maximize engine power andefficiency. Controller 12 may input engine operating conditions,including engine speed, engine load, and exhaust gas AFR, into a look-uptable and output the corresponding MBT timing for the input engineoperating conditions. In other examples the engine may ignite the chargeby compression as in a diesel engine.

In some examples, each cylinder of engine 10 may be configured with oneor more fuel injectors for providing fuel thereto. As a non-limitingexample, cylinder 14 is shown including a fuel injector 166. Fuelinjector 166 may be configured to deliver fuel received from a fuelsystem 8. Fuel system 8 may include one or more fuel tanks, fuel pumps,and fuel rails. Fuel injector 166 is shown coupled directly to cylinder14 for injecting fuel directly therein in proportion to the pulse widthof a signal FPW-1 received from controller 12 via an electronic driver168. In this manner, fuel injector 166 provides what is known as directinjection (hereafter also referred to as “DI”) of fuel into cylinder 14.While FIG. 1 shows fuel injector 166 positioned to one side of cylinder14, fuel injector 166 may alternatively be located overhead of thepiston, such as near the position of spark plug 192. Such a position mayincrease mixing and combustion when operating the engine with analcohol-based fuel due to the lower volatility of some alcohol-basedfuels. Alternatively, the injector may be located overhead and near theintake valve to increase mixing. Fuel may be delivered to fuel injector166 from a fuel tank of fuel system 8 via a high pressure fuel pump anda fuel rail. Further, the fuel tank may have a pressure transducerproviding a signal to controller 12.

Fuel injector 170 is shown arranged in intake passage 146, rather thanin cylinder 14, in a configuration that provides what is known as portfuel injection (hereafter referred to as “PFI”) into the intake portupstream of cylinder 14. Fuel injector 170 may inject fuel, receivedfrom fuel system 8, in proportion to the pulse width of signal FPW-2received from controller 12 via electronic driver 171. Note that asingle driver 168 or 171 may be used for both fuel injection systems, ormultiple drivers, for example driver 168 for fuel injector 166 anddriver 171 for fuel injector 170, may be used, as depicted.

In an alternate example, each of fuel injectors 166 and 170 may beconfigured as direct fuel injectors for injecting fuel directly intocylinder 14. In still another example, each of fuel injectors 166 and170 may be configured as port fuel injectors for injecting fuel upstreamof intake valve 150. In yet other examples, cylinder 14 may include onlya single fuel injector that is configured to receive different fuelsfrom the fuel systems in varying relative amounts as a fuel mixture, andis further configured to inject this fuel mixture either directly intothe cylinder as a direct fuel injector or upstream of the intake valvesas a port fuel injector.

Fuel may be delivered by both injectors to the cylinder during a singlecycle of the cylinder. For example, each injector may deliver a portionof a total fuel injection that is combusted in cylinder 14. Further, thedistribution and/or relative amount of fuel delivered from each injectormay vary with operating conditions, such as engine load, knock, andexhaust temperature, such as described herein below. The port injectedfuel may be delivered during an open intake valve event, closed intakevalve event (e.g., substantially before the intake stroke), as well asduring both open and closed intake valve operation. Similarly, directlyinjected fuel may be delivered during an intake stroke, as well aspartly during a previous exhaust stroke, during the intake stroke, andpartly during the compression stroke, for example. As such, even for asingle combustion event, injected fuel may be injected at differenttimings from the port and direct injector. Furthermore, for a singlecombustion event, multiple injections of the delivered fuel may beperformed per cycle. The multiple injections may be performed during thecompression stroke, intake stroke, or any appropriate combinationthereof.

Fuel injectors 166 and 170 may have different characteristics. Theseinclude differences in size, for example, one injector may have a largerinjection hole than the other. Other differences include, but are notlimited to, different spray angles, different operating temperatures,different targeting, different injection timing, different spraycharacteristics, different locations etc. Moreover, depending on thedistribution ratio of injected fuel among injectors 170 and 166,different effects may be achieved.

Fuel tanks in fuel system 8 may hold fuels of different fuel types, suchas fuels with different fuel qualities and different fuel compositions.The differences may include different alcohol content, different watercontent, different octane, different heats of vaporization, differentfuel blends, and/or combinations thereof etc. One example of fuels withdifferent heats of vaporization could include gasoline as a first fueltype with a lower heat of vaporization and ethanol as a second fuel typewith a greater heat of vaporization. In another example, the engine mayuse gasoline as a first fuel type and an alcohol containing fuel blendsuch as E85 (which is approximately 85% ethanol and 15% gasoline) or M85(which is approximately 85% methanol and 15% gasoline) as a second fueltype. Other feasible substances include water, methanol, a mixture ofalcohol and water, a mixture of water and methanol, a mixture ofalcohols, etc.

Controller 12 is shown in FIG. 1 as a microcomputer, including amicroprocessor unit 106, input/output ports 108, an electronic storagemedium for executable programs (e.g., executable instructions) andcalibration values shown as non-transitory read-only memory chip 110 inthis particular example, random access memory 112, keep alive memory114, and a data bus. Controller 12 may receive various signals fromsensors coupled to engine 10, including signals previously discussed andadditionally including a measurement of inducted mass air flow (MAF)from a mass air flow sensor 122; an engine coolant temperature (ECT)from a temperature sensor 116 coupled to a cooling sleeve 118; anexhaust gas temperature from a temperature sensor 158 coupled to exhaustpassage 148; a profile ignition pickup signal (PIP) from a Hall effectsensor 120 (or other type) coupled to crankshaft 140; throttle position(TP) from a throttle position sensor; signal EGO from exhaust gas sensor128, which may be used by controller 12 to determine the AFR of theexhaust gas; and an absolute manifold pressure signal (MAP) from a MAPsensor 124. An engine speed signal, RPM, may be generated by controller12 from signal PIP. The manifold pressure signal MAP from MAP sensor 124may be used to provide an indication of vacuum or pressure in the intakemanifold. Controller 12 may infer an engine temperature based on theengine coolant temperature and infer a temperature of catalyst 178 basedon the signal received from temperature sensor 158.

Controller 12 receives signals from the various sensors of FIG. 1 andemploys the various actuators of FIG. 1 to adjust engine operation basedon the received signals and instructions stored on a memory of thecontroller. For example, upon receiving signals from various sensors,the engine controller may send control signals to an actuator to shiftthe position of a movable sleeve relative to an active casing treatment.The signal may tell an actuator of the movable sleeve, arranged along aninlet conduit of the compressor 174 to open or close a plurality ofports disposed in the active casing treatment (as explained furtherbelow with reference to FIG. 8) in response to a current engine speedand engine load relative to a surge threshold and/or choke threshold ofthe compressor.

As described above, FIG. 1 shows only one cylinder of a multi-cylinderengine. As such, each cylinder may similarly include its own set ofintake/exhaust valves, fuel injector(s), spark plug, etc. It will beappreciated that engine 10 may include any suitable number of cylinders,including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Further, each ofthese cylinders can include some or all of the various componentsdescribed and depicted by FIG. 1 with reference to cylinder 14.

The performance of an engine may be tied to the efficiency of acompressor, with reference to engine 10 and compressor 174 of FIG. 1.The ability of the compressor to operate between a surge threshold and achoke threshold may affect the stability of the engine during low speedsas well as the power output derived from combustion of boosted air. Assuch, an active casing treatment, illustrated in detail in FIGS. 2A-2B,may relieve pressure accumulation at the outlet of the compressor duringlow engine speeds and light operation by recirculating air to the inletconduit. During heavier loads and higher engine speeds, the activecasing treatment may provide an additional channel for air flow to thecompressor past the leading edge of the compressor wheel.

A first view 200 of a compressor 202 is shown in FIG. 2A and a secondview 201 of the compressor 202 is shown in FIG. 2B. Compressor 202 is anon-limiting example of compressor 174 of FIG. 1. Compressor 202includes a central axis 208 about which an impeller 203 may be rotated.Central axis 208 may also be a central axis of an inlet conduit 210 ofthe compressor 202 defined by a housing 238 of the compressor. An airflow (e.g., intake air from an intake passage such as intake passage 142of FIG. 1) into the compressor 202 via the inlet conduit 210 isindicated by an arrow 212 which may also be a reference for thepositioning of elements relative to one another. An element in the pathof air flow relative to a reference point is considered downstream ofthat reference point and an element before the reference point in thepath of air flow is considered upstream of the said reference point. Forexample, inlet conduit 210 is upstream from impeller 203 and impeller203 is downstream from inlet conduit 210.

The impeller 203 may have a plurality of impeller blades 216 and may beconnected to a turbine, such as turbine 176 of FIG. 1, via a shaft 218that drives the rotation of the impeller 203. An outlet end of thecompressor 202 may be defined as elements of the compressor 202positioned downstream of a leading edge 232 of the impeller 203. Airthat is drawn into the compressor 202 by the rotation of the impeller203 is accelerated through a diffuser 220 and collected in a volute 222.Deceleration of gas flow in the volute 222 may cause an increase inpressure in the volute 222, resulting in gas flow to the intakemanifold.

Compressor 202 may include an active casing treatment 204 and movablesleeve 206. The active casing treatment 204 may include a casing 205surrounding a portion of the impeller 203 upstream of the leading edge232 and an inner channel 214 is formed within a cavity of the casing205. Air flowing into inlet conduit 210 passes through the inner channel214 of the casing 205 positioned within the inlet conduit 210, centeredabout the central axis 208, towards a downstream end of the innerchannel 214 where the impeller 203 is positioned.

The active casing treatment 204 may comprise a plurality of portsincluding a bleed port 228 and an injection port 230 positioneddownstream of the bleed port 228, forming channels through the casing205. The casing 205 may be a substantially cylindrical structure withopenings at a first end 224 and a second end 226. The bleed port 228 andthe injection port 230 are both disposed at the second end 226 of theactive casing treatment 204. The bleed port 228 and the injection port230 may not be continuous around the circumference of the casing, butmay be interrupted by one or more ribs 246 connecting the casingupstream of the second end 226 to the outlet end of the compressorhousing. As such, each of the bleed port 228 and the injection port 230may include a plurality of ports arranged around the circumference ofthe casing 205.

A width of the injection port 230, measured along the central axis 208,may be larger than a width of the bleed port 228. The bleed port 228 andinjection port 230 are arranged downstream of the leading edge 232 ofthe impeller 203 and each port fluidly couples the inner channel 214 ofthe casing 205 to one of two chambers positioned outside of the casing205. Specifically, the bleed port 228 fluidly couples the inner channel214 to a first chamber 234 formed between an outer surface of the casing205 and an inner surface of the movable sleeve 206. The injection port230 fluidly couples the inner channel 214 to a second chamber 236positioned between an outer surface of the movable sleeve 206 and aninner surface of the compressor housing 238.

As elaborated below, during conditions when compressor surge may occur,such as at low mass flow conditions, active casing treatment 204 mayenable gas to flow from the second end 226 of inner channel 214 throughbleed port 228 into first chamber 234. The gas further continues fromfirst chamber 234 into the first end 224 of inner channel 214. Thus,when the bleed port is open, the flow of gas striking the leading edge232 of impeller 203 may be greater than the flow of gas through theinner channel 214 to the leading edge 232 without additional air flowthrough bleed port 228 (e.g., when the bleed port is blocked). Theadditional flow of recirculating gas may enable the turbochargercompressor to operate with a lower air flow through intake conduit 210before surge occurs.

The first chamber 234 may comprise noise deflecting elements such as anumber of protrusions extending radially from an outer surface of thecasing 205 into the first chamber 234. Alternatively, noise producedduring recirculation flow may be dampened by a single noise deflectorattached to the outer surface of the casing 205 that curves into thepath of air flow. In other examples, the noise arising from flow throughthe first chamber 234 may be reduced by configuring the first chamber234 with structures that alter a volume of the first chamber 234 or avelocity of air flow therethrough.

During conditions when compressor choke may occur, such as at high massflow conditions, active casing treatment 204 may enable gas to flow inthe same direction as flow through the inner channel 214 but through analternate pathway via a second chamber 236 and injection port 230 toreach the impeller 203. During high mass flow conditions, a low pressurezone may be present in inner channel 214 downstream of the leading edgeof impeller 203 adjacent to injection port 230. The low pressure zonemay induce gas to flow from inlet conduit 210 through second chamber 236and then to the impeller 203 via injection port 230. The path throughsecond chamber 236 may enable the flow of gas through the compressor 202to be increased at high mass flow conditions when compared to acompressor without injection port 230. In this way, the additional flowof gas may enable more gas to be delivered to the compressor 202 beforethe compressor chokes and/or may relieve choked flow.

The movable sleeve 206 may be adapted to circumferentially surround thecasing 205 and separates the first chamber 234 from the second chamber236. The movable sleeve 206 is a cylindrical structure with a first end240 and a second end 242 that both curve inward towards the central axis208 so that a central portion 244 of the movable sleeve 206 is spacedaway from the outer surface of the casing 205. The inner surface of themovable sleeve 206 may also include ribs 246 arranged along the centralportion 244 that projects into the first chamber 234. The ribs maycontact the casing 205 to maintain alignment of sleeve 206 concentricwith casing 205.

The first chamber 234 is formed from the space between the movablesleeve 206 and the casing 205 and may be smaller than the second chamber236. Specifically, the inner volume of the first chamber 234, which isfurther reduced by the arrangement of the ribs 246 within, as well asthe length, diameter, and circumference of the first chamber 234, mayeach be smaller than those of the second chamber 236. The inner volumeof the first chamber 234 may also be smaller than the inner volume ofthe casing 205, thus the amount of air that may flow through the firstchamber may be less than the amount flowing through the inner channel214 of the casing 205. In comparison, the second chamber 236 may have aninner volume greater than that of the first chamber 234 but less thanthe inner volume of the casing 205, allowing less air to flow throughthe second chamber than through the inner channel 214, at least duringsome conditions.

Air flow may be directed through either the first chamber 234 or secondchamber 236 by varying the position of the movable sleeve 206 relativeto the casing 205. The movable sleeve 206 may be configured to extendaxially along the central axis 208 so that the first end 240 of themovable sleeve 206 is upstream of the first end 224 of the casing 205.The second end 242 of the movable sleeve 206 may alternate betweenaligning with the injection port 230, as shown in FIG. 2A, and aligningwith the bleed port 228, as shown in FIG. 2B, when actuated to moveaccording to engine operations. As the movable sleeve 206 is shiftedaxially, the second end 242 slides along the outer surface of the casing205 and seals either the bleed port 228 or injection port 230, blockingflow between the inner channel 214 and either the first chamber 234 orsecond chamber 236, respectively.

In this way, the movable sleeve 206, in combination with the activecasing treatment 204, may prevent both compressor surge and choke byenabling air flow through channels disposed at the downstream end of thecasing 205 in the inlet conduit 210, adjacent to the impeller 203. Theshape of the movable sleeve 206 with the second end 242 curving inwardstowards the casing 205 allows the second end 242 to be in face-sharingcontact with the outer surface of the casing 205. For example, thesecond end 242 includes a face that extends in a cylinder coaxially withthe axis 208 that contacts (e.g., shares a face with) the outer surfaceof casing 205. The face is sized to block the fluidic coupling betweeninjection port 230 and second chamber 236 when movable sleeve 206 is inthe first position shown in FIG. 2A, or to block the fluidic couplingbetween bleed port 228 and first chamber 234 when movable sleeve 206 isin the second position shown in FIG. 2B. In this way, the movable sleeve206 is able to alternate between sealing bleed port 228 or injectionport 230 when positioned accordingly. The adjustment of the movablesleeve 206 specific to each of a lower and upper limiting boundary ofcompressor operation is further described below.

The movable sleeve 206 may be moved to the position shown in FIG. 2Awhere the second end 242 is blocking the injection port 230 forcompressor operation at or outside of the lower surge limit (e.g., tothe left of the surge limit) as according to the compressor map shown inFIG. 9. As a non-limiting example, operating the engine at relativelyhigh loads and low engine speeds may lead to the compressor 202operating at the surge limit or within the surge region. Pressure mayaccumulate at the outlet end of the compressor 202 and force a reversalin air flow. This reversal may cause degradation of the turbocharger andpressurized air may be violently vented out through the inlet conduit210, accompanied by loud vibrations.

To alleviate the formation of a high pressure zone, air may berecirculated through the first chamber 234, as indicated by arrows 248,in a direction opposite of flow through the inner channel 214. Air flowsfrom the region adjacent to the impeller 203 through the bleed port 228,to return to the first end 224 of the casing 205. The air flow thenproceeds to re-enter the inner channel 214, flowing once again to theimpeller 203. The bleed port 228 thus acts as a vent to “bleed” excesspressure accumulating at the outlet end of the compressor 202 uponoperating below the compressor's surge limit. The arrangement of theleading edge of the sleeve 206 restricts and dampens oscillations in thesurge flow so that noise is minimized and redirected into the compressorrather than projecting upstream to the atmosphere.

The relatively narrow bleed port 228 and small inner volume of the firstchamber 234 in comparison to the inner channel 214 of the casing 205 mayconstrain flow through the first chamber 234 to a small portion of thetotal air flow through the compressor 202. In one example, when themovable sleeve 206 is adjusted to open the bleed port 228 and close theinjection port 230, 5% of the air flowing to the impeller 203 isrecirculated through the bleed port. As another example, the fraction offlow recirculated through the bleed port 228 may be 2%, 10% or 15% ofthe total flow through the compressor. Flow is further restrictedthrough the first chamber 234 by the incorporation of the ribs 246 inthe path of flow. During certain engine operations, e.g., cruising oraccelerating, the bleed port 228 remains open and maintains a pressureequilibrium across the compressor by enabling the slow and constantrecirculation of air.

In contrast, during conditions that push the compressor to approach orsurpass the choke limit, the movable sleeve 206 is actuated to theposition shown in FIG. 2B. Conditions leading to turbocharger choke mayinclude sudden increases in engine load, a degraded wastegate,engine/turbocharger mismatch, etc. With the bleed port 228 sealed by thesecond end 224 of the movable sleeve 206, recirculation of air via thefirst chamber 234 is blocked. Air enters inlet conduit 210, flowingthrough inner channel 214 to the impeller 203, with an additional amountof air delivered to the region adjacent to the impeller 203 via thesecond chamber 236 (following arrows 250) and the injection port 230.The injection port 230 is located in a region that often experiences lowpressure during high flow and the low pressure assists in drawing airinto the second chamber 236 towards the injection port 230. Furthermore,the second chamber 236 has a larger inner volume than the first chamber234, as described above, and the width of the injection port 230 may beconfigured so that enough extra air may be channeled through the secondchamber 236 and injection port 230 to efficiently deliver the demandedairflow to the intake manifold of the engine.

By providing an alternate pathway via the second chamber 236 andinjection port 230 that is separate from the surge recirculation route(comprising the bleed port 228 and first chamber 234), faster and highervolume air flow to mitigate turbocharger choke is enabled duringcompressor operation at or beyond a pre-set choke limit. The sonic speedof air flowing through inner channel 214 of the compressor 202 thatoften leads to compressor choke may be alleviated by providingadditional airflow to the region adjacent to the impeller 203 in a samedirection as flow through the inner channel 214 of the casing 205.Together, the active casing treatment 204 and movable sleeve 206 ofFIGS. 2A-2B improve the efficiency and performance of the compressor 202by extending the surge and choke limits as well as the experience ofvehicle passengers by reducing noise during light engine loads.

The adjustment of the movable sleeve described above to align withelements of the active casing treatment may be accomplished by couplingthe movable sleeve with an actuating device. An example of such a deviceis illustrated in FIG. 3, showing the compressor 202 of FIGS. 2A-2Badapted with a rotary actuator 306 coupled to the movable sleeve 206.Elements in common with those of FIGS. 2A-2B are similarly numbered. Themovable sleeve 206 includes a central axis 208 which may also be acentral axis of the compressor 202 about which the impeller (not shownin FIG. 3) may be rotatable (e.g., the central axis 208 is the axis ofrotation of the impeller). The direction of air flow into inlet conduit210 of compressor 202 is shown by the arrow 212. A set of reference axes302 is provided for comparison between views shown in FIGS. 3-7B,indicating a “y” vertical direction, “x” horizontal direction, and “z”lateral direction.

The movable sleeve 206 may be a cylindrical shell configured to surroundthe casing (not shown in FIG. 3) within the inlet conduit 210 ofcompressor 202. A length of the movable sleeve 206, as defined in thelateral direction of reference axes 302, extends axially along the inletconduit 210. The moveable sleeve is spaced away from an inner surface ofthe compressor housing 238 which circumferentially surrounds both theinlet conduit 210 and the movable sleeve 206. The space between theinner surface of the compressor housing 238 and an outer surface of themovable sleeve 206 forms the second chamber 236 that allows additionalair flow to be delivered to the impeller during high load engineoperations. As such, the movable sleeve 206 may be adjusted to blockflow through the bleed port of the active casing treatment and allowflow through the injection port. A space between an inner surface of themovable sleeve 206 and the casing may define the first chamber, throughwhich recirculation of flow, in a direction opposite of the air flowindicated by arrow 212, may occur during light engine loads via thebleed port. The inner surface of the movable sleeve 206 may include ribstructures to center the sleeve around the housing while creating thespace allowing airflow to occur. In one example, the structures may bethe ribs 246 shown in FIGS. 2A-2B. The arrangement of the first end ofthe sleeve 240 restricts and dampens oscillations in the surge flow sothat noise is minimized and redirected into the compressor rather thanprojecting upstream to the atmosphere. The outer surface of the movablesleeve 206 may be attached to a linkage 318 of the rotary actuator 306.The rotary actuator 306 may be arranged external to the inlet conduit210 of the compressor 202 and adjacent to the inlet end 322 of thecompressor housing 238, spaced away from the inlet end 322 by a lengthof the linkage 318. The linkage 318 may include a first branch 316, asecond branch 319, a third branch 320, and an arm 326 that is coupled toa motor 328 of the rotary actuator 306. The first branch 316 may includea plurality of sections arranged in an alternating pattern ofperpendicular alignment and couples to an outer surface of the movablesleeve 206. The first branch 316 may extend through the inlet end 322 ofthe compressor housing 238 via an aperture in the inlet end 322 with aportion of the first branch 316 protruding outside of the compressorhousing 238. The first branch is constrained to rotate about an axisperpendicular to central axis 208 which traverses from inside to outsideof the compressor housing 238. An end of the first branch 316 of thelinkage 318 that protrudes outside of the compressor housing 238connects to a first end of the second section branch 319. The secondbranch 319 is arranged entirely outside of the compressor housing 238.The second branch 319 rotates about the same axis as branch 316 andcouples at a second end to the third branch 320 that extends in adirection away from the inlet end 322 of the compressor housing 238,approximately perpendicular to the central axis 208. In anotherembodiment, branch 320 may extend in a different direction such astoward the inlet end 322. The third branch 320 is also entirely outsideof the compressor housing 238. The third branch 320 connects at one endto an arm 326 that is connected to a motor 328 of the rotary actuator306. The motor 328 is configured to rotate the arm 326 to vary theposition of the attached movable sleeve 206. The pivoting of the arm 326may translate to both an axial and rotational movement of the movablesleeve 206 via the linkage 318 and is explained in further detail in thefollowing descriptions of FIGS. 4A-4B.

Side views of the inlet conduit 210 of the compressor 202 areillustrated in FIGS. 4A-4B. Components common to compressor 202 of FIGS.2A-3 are similarly numbered. The inlet conduit 210 is surrounded by theinlet end 322 of the compressor housing. An outer surface 404 of themovable sleeve 206 in FIGS. 4A-4B is shown attached to a pin 412 of thefirst branch 316 of the linkage 318. A first end of the pin 412 may beinserted into a hole in the outer surface 404 of the movable sleeve 206,thereby fixing the first end of the pin 412 to the movable sleeve 206.The pin 412 may include a surface shape such as a portion of a sphere inorder to appropriately couple with the movable sleeve 206. In additionto the pin 412, the first branch 316 may also include a second section414 and a stem 416. The pin 412 of first branch 316 extends outwardsfrom the movable sleeve 206 in a direction perpendicular to the centralaxis 208. A second end of pin 412 is coupled to a first end 413 of thesecond section 414 of the first branch 316.

The second section 414 is perpendicular to the pin 412 and may extendalong a length of the movable sleeve 206, the length being defined inthe direction of flow as indicated by arrow 212. The second section 414is positioned so that the first end 413 is downstream, along the outersurface 404 of the movable sleeve 206, of a second end 415. As such, thepin 412 is arranged downstream of the stem 416 of the first end 316 ofthe arm 318.

The second end 415 of the second section 414 couples to the stem 416which is parallel with the pin 412 of the first branch 316. The stem 416of the first branch 316 extends outwards and away from the outer surface404 of the movable sleeve 206 so that a portion of the stem 416 isinside the inlet end 322 of the compressor housing and a portion isoutside of the inlet end 322. An end of the stem 416 that is external tothe inlet end 322 is connected to the second branch 319 by a first hinge408. The first hinge 408 may be a fixed connection point between thefirst branch 316 and second branch 319. Specifically, an angle 420formed by the second branch 319 and the second section 414 of the firstbranch 316 is rigid and does not vary as the linkage 318 is pivoted bythe rotary actuator 306. The angle 420 may be any appropriate angledepending on the dimensions and placement of the linkage 318 and themovable sleeve 206. In contrast, the second branch 319 may couple to thethird branch 320 at a second hinge 410 that is not rigid. In otherwords, an angle formed between the third branch 320 and second branch319 may change as the linkage 318 is pivoted.

The movable sleeve 206 in FIG. 4A is depicted in a position that mayclose the bleed port and allow flow through the injection port,corresponding to the second position shown in FIG. 2B of the movablesleeve and hereafter will be referred to as a second position (e.g.,open for flow during turbocharger choke). When the linkage 318 ispivoted to a first position as shown in FIG. 4B and corresponding to thefirst position shown in FIG. 2A of the movable sleeve, where the bleedport is open to flow and the injection port is blocked, the third branch320 shifts in a direction indicated by arrow 418 illustrated in FIG. 4A.This motion results in the tilting of the second branch 319 so that anupstream end of the second branch 319 is above the central axis 208which in turn pivots the first branch 316 at the rigid first hinge 408so that the pin 412 of the first branch 316 swings downwards through anarc, indicated by arrow 420. The attachment of the pin 412 to the outersurface 404 of the movable sleeve 206 results in rotation of the movablesleeve by a distance 422 in a direction perpendicular to the centralaxis 208 and an axial shift by a distance 424 in a downstream directioncoaxial with the central axis 208. The movable sleeve 206 is thusactuated from the second position shown in FIG. 4A to the first positionshown in FIG. 4B.

To move the movable sleeve 206 from the first position (FIG. 4B) to thesecond position (FIG. 4A), the linkage 318 may be pivoted so that thethird branch 320 shifts downwards in the direction indicated by arrow426. This translates into swinging the pin 412 of the first branch 316through an upwards arc indicated by arrow 428. The movable sleeve 206 isshifted rotationally by the distance 422 and axially by the distance 424in opposite directions from the movements described for FIG. 4A, thusactuated to the second position.

The motion of the rotary actuator 306 is shown in additional detail inFIGS. 6A-6B. A first schematic 600 depicts a top view of the movablesleeve 206 and rotary actuator 306 adjusted to the second position and asecond schematic 650 represents a top view of the movable sleeve 206 androtary actuator 306 in the first position. Direction of air flow throughthe movable sleeve is indicated by arrow 212. The movable sleeve 206 hasthe central axis 208 and is attached to the first branch 316 of thelinkage 318 via a first end (e.g., the pin 412 of the first branch 316of FIGS. 4A-4B). The linkage 318 links the movable sleeve 206 to therotary actuator 306.

The rotary actuator 306 may be coupled to the arm 326 through the motor(not shown in FIGS. 6A-6B) which pivots the arm 326. A first end 602 ofthe arm 326 is connected to the motor and forms a joint that is an axisabout which the arm 326 may be pivoted/rotated along the plane formed bythe horizontal direction and lateral direction, with respect to the setof reference axes 302. A second end 603 of the arm 326 couples to thethird branch 320. To shift the movable sleeve 206 from the secondposition of FIG. 6A to the first position of FIG. 6B, the second end 603of the arm 326 may rotate in the direction indicated by arrow 604 ofFIG. 6A, driving a linear motion of the third branch 320 in thedirection shown by arrow 418 of FIG. 6A. The third branch 320 is coupledto the second branch 319 at the second hinge 410. The second branch 319and first branch 316, arranged at a fixed angle, pivot about first hinge408 so that the end of the first branch 316 that is attached to themovable sleeve 206 swings through an arc indicated by arrow 420. Themovable sleeve 206 shifts rotationally by distance 422 and downstreamaxially by distance 424, as described above, into the first positionshown in FIG. 6B. To actuate the movable sleeve 206 from the firstposition to the second position (e.g. from the configuration of FIG. 6Bto the configuration of FIG. 6A), the rotary actuator 306 may pivot thearm 326 at the first end 602 through the arc shown by arrow 606 of FIG.6B to slide the third branch 320 in the direction indicated by arrow426, thereby swinging the first branch 316 through the arc shown byarrow 428.

First and second schematics 600 and 650 show that an angle between thearm 326 and the third branch 320 as well as an angle between the thirdbranch 320 and the second branch 319 may vary as the arm 316 is pivotedby the rotary actuator 306. The angle between the second branch 319 andthe first branch 316 is fixed, however, which enables the translation ofthe pivoting of the arm 326 into the swinging of the first branch 316 ofthe linkage 318, which is further converted to the rotational and axialshifting via a single actuation motion of the movable sleeve 206.

The positioning of the first branch 316 of the linkage 318 with respectto the movable sleeve 206 and inlet conduit 210 is shown from a frontsection view in FIG. 5. The first branch 316 is attached to the outersurface 404 of the movable sleeve 206 at the pin 412 (not shown in FIG.5). The inlet end 322 of the compressor housing has an inner surface 402and the space between the inner surface 402 and an outer surface 404 ofthe movable sleeve 206 forms the second chamber 236.

The movable sleeve 206 circumferentially surrounds the casing 205 whichmay include the active casing treatment as described above with respectto FIGS. 2A-2B, at a downstream end of the casing 205. The first chamber234 is formed in the space between the inner surface of the movablesleeve 206 and the outer surface of the casing 205 and has an innervolume smaller than either an inner volume of the second chamber 236 orthe inner channel 214 of the casing 205. Ribs 246 protrude into thefirst chamber 234 from the inner surface of the movable sleeve 206.

The attachment of the pin 412 to the outer surface 404 of the movablesleeve 206, the rigid coupling of the first branch to the second branchof the linkage 318, as well as an alignment of the linkage 318 withrespect to the movable sleeve 206, enables both an axial and arotational adjustment of the movable sleeve 206 in a single actuatingmotion. The positioning of the stem 416 of the first branch 316,represented by a dashed line 407, is offset from a bisecting line 405(dividing the inlet conduit 210 in half) by a distance 409, defined in adirection perpendicular to the bisecting line 405. In one position, suchas the position of the linkage 318 shown in FIG. 4A, the pin 412 may bealigned to the left of the bisecting line 405 by an amount approximatelyequal to one half of the rotational distance 422. In a second position,such as the position of the linkage 318 shown in FIG. 4B, the pin 412may be aligned to the right of bisecting line 405 by an amountapproximately equal to one half of the rotational distance 422. In thisway, the depth of engagement of pin 412 into sleeve 206 is similar atboth selectable positions.

The movable sleeve 206 of FIGS. 2A-6B may also be adapted to move viaactuating mechanisms other than the rotary actuator shown. For example,as illustrated in FIGS. 7A-7B, a first schematic 700 top-down view ofthe movable sleeve 206, shows the movable sleeve 206 coupled to a linearactuator 702 in the second position. A second schematic 750 of themovable sleeve 206 and linear actuator 702 depicts the movable sleeve206 in the first position. Flow through the movable sleeve 206 isindicated by arrow 212 and the central axis 208 is included in both thefirst schematic 700 and second schematic 750.

The linear actuator 702 may be positioned external to the inlet conduit,above the movable sleeve 206 with the body of the linear actuator 702upstream of the moveable sleeve 206, and offset from central axis 208. Amotor 704 of the linear actuator 702, and a retractable arm 706,extending out from the motor 704, are parallel with the central axis208. The linear actuator 702, similar to the rotary actuator of FIGS.6A-6B, may include the linkage 318 configured with the first branch 316,second branch 319, and third branch 320. The second branch 319 and thirdbranch 320 may be arranged outside of the inlet conduit while the firstbranch 316 may extend through the compressor housing.

The first branch 316 is attached to the movable sleeve 206 at one endand may extend through the compressor housing so that a portion of thefirst branch 316 protrudes outside of the compressor housing. The end ofthe first branch 316 that that is outside of the compressor housing iscoupled to the second branch 319 by the first hinge 408 so that theangle between the first branch 316 and second branch 319 is constant.The second branch 319 of the linkage 318 is coupled to the third branch320, both of which may be arranged outside of the compressor housing.

The retractable arm 706 may connect the third branch 320 to the motor704. The retractable arm 706 and the third branch 320 may be coupled sothat the angle between the retractable arm 706 and third branch 320 isnot fixed. The motor 704 activates a linear motion of the retractablearm 706 that is parallel with the central axis 208. For example, toactuate the movable sleeve 206 from the open position, shown in FIG. 7A,to the closed position of FIG. 7B, the motor 704 may retract theretractable arm 706 in a direction indicated by arrow 708. The movementof the retractable arm 706 results in the shifting of the third branch320 also in the direction of arrow 708. The change in position of thethird branch 320 may pull the second branch 319 at an end connected tothe third branch 320 so that the end of the second branch 319 rotatesupwards, indicated by arrow 710 of FIG. 7A. The first branch and secondbranch 319, connected at the first hinge 408, may pivot as a single unitabout the first hinge 408 and swing the first branch 316 through the arcshown by arrow 712. The curved motion of the first branch 316 results inthe shifting of the attached movable sleeve 206 by the rotationaldistance 422 and the axial distance 424 in a downstream direction.

To actuate the movable sleeve 206 from the closed position to the openposition, e.g., from the position of FIG. 7B to the position of FIG. 7A,the linear actuator 702 may activate the motor 704 to extend theretractable arm 706 in a direction shown by arrow 714 of FIG. 7B. Thethird branch 320 is also shifted in the direction of arrow 714, therebypivoting the end of the second branch 319 that is connected to the thirdbranch 320 as indicated by arrow 716. The first branch 316 is thuspivoted in an upwards direction along an arc shown by arrow 718,resulting in the rotation of the movable sleeve 206 by the distance 422and movement through an axial distance 424 in an upstream direction.

In the examples of FIGS. 7A-7B, the linkage 318 may have the firstbranch 316, second branch 319 and third branch 320 similar to thelinkage of the rotary actuator shown in FIGS. 6A-6B. The orientations ofthe branches of the linkage 318, however, may differ due to thepartially upstream arrangement of the linear actuator 702 above andaligned along the length of the movable sleeve 206 instead of beside themovable sleeve as for the rotary actuator. In the first and secondschematics 700 and 750 showing the linear actuator 702, the retractablearm 706 and third branch 320 are nearly coaxial but are not fixed withrespect to the angle formed between the retractable arm 706 and thirdbranch 320. In the first and second schematics 600 and 650 of the rotaryactuator 306, however, the arm 326 pivots so that the angle of the arm326 relative to the third branch varies from an acute angle, as shown inFIG. 6A, to an obtuse angle, shown in FIG. 6B. The rotary actuator 306of FIGS. 3-6B and linear actuator 702 of FIGS. 7A-7B both enable therotational and axial displacement of the movable sleeve 206 and theoptional positioning of the actuator may accommodate differentallowances in available space around the compressor housing. Otherarrangements of the position of a rotary or linear actuator are possibleand may be selected based on the available space for packaging anactuator proximate the compressor housing.

In this way, a movable sleeve may be adjusted to either allowrecirculation flow during light engine loads or to enable additionaldelivery of air to an impeller when a compressor is operating under highloads. The position of the movable sleeve shown in FIGS. 4A, 6A, and 7Amay correspond to the actuation of a linkage connecting the movablesleeve to an actuator during high engine loads with the movable sleeve206 positioned to block flow through a bleed port, arranged upstream ofan injection port of an active casing treatment. The injection port isthus open to flow of air through a second chamber in a same direction asthe flow into an inlet conduit of the compressor. Upon receiving asignal from a controller, for example, during reduced engine load, thelinkage of the actuator may shift the movable sleeve an axial distanceas well as a rotational distance. Flow through the injection port isblocked while the bleed port is opened so that air may be channeled froma region adjacent to the impeller back into the inlet conduit in adirection opposite of flow through the inlet conduit. The rotationaldistance that the movable sleeve travels with each adjustment ofposition may prevent the binding of the movable sleeve to a casing, inwhich the active casing treatment is arranged, in the event thatmaterial accumulates between the movable sleeve and casing over time.

Turbocharger compressors may operate according to an operating map ofcompressor pressure ratio as a function of mass flow rates such as thecompressor map 900 shown in FIG. 9. The X axis represents flow rate, andthe Y axis represents pressure ratio, or the output pressure divided byinput pressure. At the left side of the map, the surge line, denoted bydashed line 902, or surge limit, represents where the compressoroperation may lose stability and exhibits surge behavior ranging fromwhoosh noise to violent oscillations of flow. At the right side of themap, the compressor is limited by choked flow conditions at the inlet tothe compressor, as shown by dashed line 904 representing the choke lineor choke limit. Operation to the left may be extended by including ableed port in the compressor casing just downstream of the leading edgeof the compressor wheel. Under low flow conditions, this port allowssome air flow to recirculate outside the main flow path to a pointfurther upstream and later be reintroduced to the compressor. Withproper flow channeling, this recirculating flow is quieter thanrecirculating flow that would occur near the surge limit without thebleed port. Under high flow conditions, air flow may be circulatedthrough a different port in the casing further downstream of the typicalbleed port. This second port (injection port) is in an area known toexperience relatively low air pressure during high flow conditions whichallows additional air to flow forward into the compressor wheel when thenormal flow is nearly choked. This injection port may be blocked toprevent backward (recirculating) flow from occurring at other operatingpoints on the map, otherwise decreased compressor efficiency may result.Thus, the moveable sleeve described herein allows the injection port tobe selectively covered or exposed while also allowing a flow path forthe bleed port that minimizes noise projecting upstream in the air path.

The present disclosure describes a compressor casing with two ports—onefor surge, one for choke—along the compressor wheel. A thin cylindricalsection of the casing extends upstream from the compressor wheel. Theports are circumferential in the casing except for a limited number ofspokes or supports to carry the material upstream of each port. A sleeveis installed surrounding the protruding cylinder casing. In a firstposition, the sleeve includes features to cover the injection port andto direct the surge recirculation flow from the bleed port to anupstream location pointed back toward the compressor wheel. In thesecond position, the sleeve is moved enough to expose the injection portand may cover the bleed port. In order to prevent binding, the sleevemay rotate at the same time as the sleeve moves axially. The mechanismto provide this motion includes a linkage through the turbochargercompressor housing. The linkage moves a first end of the linkage throughan arc. The first end of the linkage is fixed to the sleeve such that asthe first end sweeps through the arc, it rotates and translates thesleeve.

Turning to FIG. 8, a flow chart of a method 800 for controllingoperation (e.g. controlling a flow through and a position) of an activecasing treatment in combination with a movable sleeve arranged in aninlet conduit of a compressor is shown. Specifically, the active casingtreatment may be active casing treatment 204 and the movable sleeve maybe movable sleeve 206 of FIGS. 2A-2B. The movable sleeve maycircumferentially surround a casing in which the active casing treatmentis disposed and the movable sleeve and casing may be positioned in aninlet conduit of a compressor, as shown in FIGS. 2A-2B, upstream of animpeller. A first chamber, fluidly coupled to a bleed port of the activecasing treatment, may be formed from the space between an outer surfaceof the casing and an inner surface of the movable sleeve. Air mayrecirculate, when the bleed port is open, from a region adjacent to theimpeller through the bleed port and first chamber to the inlet conduit.A second chamber, fluidly coupled to an injection port of the activecasing and formed from the space between an outer surface of the movablesleeve and an inner surface of a compressor housing, may allowadditional air flow to be delivered to the impeller region when theinjection port is open. Instructions for carrying out method 800 and therest of the methods included herein may be executed by a controller(e.g., controller 12 shown in FIG. 1) based on instructions stored on amemory of the controller and in conjunction with signals received fromsensors of the engine system, such as the sensors described above withreference to FIG. 1. The controller may employ engine actuators of theengine system to adjust engine operation, according to the methodsdescribed below. For example, the controller may employ an actuator ofthe movable sleeve to adjust the position of the movable sleeve so thateither the bleed port or injection port is open to air flow, as shown inFIGS. 2A-2B. An example of such an actuator is shown in FIG. 3, asdescribed above and the operation of the movable sleeve and activecasing treatment via the actuator is described in the method below.

At 802, the method includes estimating and/or measuring engine operatingconditions. Engine operating conditions may include engine speed, engineload, intake air mass flow, engine temperatures (such as engine coolanttemperature), intake manifold pressure, a pressure differential acrossthe compressor, a position of the movable sleeve, etc. At 804, themethod includes determining whether current compressor operation isbelow a surge threshold. Current compressor operation below a surgethreshold may be determined based on a current (e.g., currentlydetermined) engine load and engine speed being below a surge line orthreshold. For example, a map of engine load vs. engine speed or alook-up table may be stored in a memory of the controller. Thecontroller may determine the current engine speed (based on a profileignition pickup signal from Hall effect sensor 120 of FIG. 1, forexample) and engine load (based on output from MAP sensor 124, the pedalposition signal, and/or other parameters) and then look up whether thisoperating point is above or below the surge threshold. In one example,the surge threshold may be a pre-set surge threshold stored in the mapor look-up table.

In another example, compressor operation below a surge threshold may bedetermined according to a compressor map that plots compressor pressureratio as a function of compressor mass flow. For example, referring toFIG. 9, the surge limit is represented by dashed line 902. The surgethreshold may be defined as a line on the compressor map that represents20% more flow than the flow at the surge limit line. The area to theleft of dashed line 902 is a region where the compressor operates belowa surge limit that encompasses a range of pressure ratios relative toflow rate that are lower than the minimum flow rate for stablecompressor operation. Operating near the surge limit results ininefficient compressor operation and in some cases unfavorable noise.Setting a surge threshold above the surge limit allows some margin andmay prevent operation in an unfavorable region of the compressor map.

Additionally, as used herein, the compressor operating below the surgethreshold may include the compressor operating to the right of a surgelimit, as shown in FIG. 9 and explained above, but within a thresholdrange of the surge limit (e.g., within a threshold mass air flow of thesurge limit). Further, the compressor may operate with the movablesleeve adjustable to open flow through the bleed port in the firstposition for a range of compressor operating conditions until the chokelimit is approached.

If the compressor is operating below the surge threshold, the methodcontinues to 806 to adjust the movable sleeve to a first position thatopens the bleed port. Adjusting the movable sleeve may include thecontroller sending an electronic signal to an actuating mechanism of themovable sleeve to either slide the movable sleeve from a position wherethe injection port is open (and the bleed port is closed, referred to asthe second position of the movable sleeve) to the first position wherethe bleed port is open, or to maintain the movable sleeve in the firstposition where the bleed port remains open. The arrangement of themovable sleeve so that the bleed port is open is shown in FIGS. 2A and4B, as described above. As explained above with reference to thesefigures, when the bleed port is open, pressure at an outlet end of thecompressor (as defined as downstream of a leading edge of the compressorimpeller) is alleviated by allowing flow from the impeller regionthrough the bleed port and first chamber to return flow to the inletconduit, as indicated at 808 of FIG. 8. The first chamber may be adaptedwith elements, such as first end 240 of the movable sleeve 206 shown inFIGS. 2A-2B, to reduce noise and dampen oscillations during surge flow,e.g., flow through the first chamber in the opposite direction of flowthrough the inlet conduit. By adjusting the movable sleeve to open thebleed port and close the injection port, the surge limit of thecompressor may be shifted such that more engine operating points may beoutside of the surge region and noise is suppressed.

Alternatively at 804, if the engine is operating above the surgethreshold, the method proceeds to 810 to determine whether turbochargeroperation is above a choke threshold. Turbocharger choke may occur whenthe engine experiences high loads and speeds, high air flow, or otherparameters leading to air flow into the compressor above the toleranceof the turbocharger (e.g., above the amount of air flow the compressoris physically adapted to flow). During choke, air velocity entering thecompressor wheel may nearly reach the speed of sound, preventing anyincrease in airflow. Input from various sensors as described above fordetection of compressor surge may also be used to evaluate whethercompressor operation exceeds a choke threshold (e.g., engine speed andload, compressor mass flow and pressure ratio). The choke threshold mayalso be a pre-set threshold stored in a map of engine load vs. enginespeed, compressor ratio vs. mass flow, or in a look-up table. Forexample, referring to FIG. 9, the choke threshold or choke limit isdelineated by dashed line 904. The region to the right of dashed line904 represents conditions exceeding the choke threshold. If theturbocharger is determined to be operating below the choke threshold(e.g., to the left of the choke threshold), method 800 proceeds to 806such that the controller may send a signal to the actuating mechanism toadjust the movable sleeve so that the bleed port is open or remains openand the routine continues to 808.

If the controller determines that compressor operation exceeds the chokethreshold (e.g., the compressor is operating to the right of the chokeline of FIG. 9), the method continues to 812 where the movable sleeve isactuated to the second position to open the injection port and close thebleed port. Additionally, as used herein, the compressor operating abovethe choke threshold may include the compressor operating to the right ofa choke limit, as shown in FIG. 9 and explained above, but within athreshold range of the choke limit (e.g., within a threshold mass airflow of the choke limit). Further, in some examples, the movable sleevemay be adjusted to open the injection port when compressor operationnears the choke limit but the compressor is not operating in the chokeregion, e.g., if the compressor mass flow and pressure ratio are within5 or 10% of the choke threshold.

At 814, air flows from the inlet conduit to the impeller region by wayof the second chamber and injection port. This enables additional airflow to be delivered to the impeller of the compressor, thereby reducingthe velocity of air flowing into the leading edge of the compressorwheel which reaches nearly the speed of sound during choke. The secondchamber does not include noise suppression structures and thus does notrestrict flow.

After enabling flow through the injection port of the active casingtreatment, the method proceeds to 816 to determine whether turbochargeroperation is still above the choke threshold. If the choke threshold isstill exceeded, the method returns to 812 to maintain the movable sleevein the second position where the injection port is open to flow. If,however, engine operation falls below the choke threshold, the routinecontinues to 818 to adjust the movable sleeve to the first position toopen the bleed port and allow recirculation of air through the firstchamber to return to the inlet conduit. In some examples, the controllermay maintain the movable sleeve in the second position until theturbocharger operation is below the choke threshold by a suitableamount, such as 5 or 10% below the choke threshold.

In this way, a movable sleeve coupled with an active casing treatmentpositioned within an inlet conduit of a compressor and upstream of animpeller of the compressor may be used to adjust the flow through theinlet conduit. The movable sleeve circumferentially surrounds a casing,in which the active casing treatment is disposed, and is itselfsurrounded by a compressor housing. The movable sleeve is spaced awayfrom both the casing and the compressor housing, so that a first chamberis formed between the casing and the movable sleeve that is fluidlycoupled to a bleed port in the active casing treatment. The firstchamber may be adapted with noise suppressing structures such asrestrictors or deflectors. A second chamber is formed from the spacebetween the movable sleeve and the compressor housing. The secondchamber is fluidly coupled to an injection port in the active casingtreatment. In one example, the movable sleeve may be adjusted to allowflow through the bleed port but not the injection port when turbochargeroperations (e.g., compressor mass flow and pressure ratio) are below achoke threshold and/or below a surge threshold. In this position, airflow is allowed to recirculate from the impeller to the inlet conduitvia the bleed port and first chamber, relieving pressure accumulation atan outlet end of the compressor and extending the surge margin as wellas dampening oscillations generated during surge flow. In anotherexample, the movable sleeve may be adjusted to open flow through theinjection port but not the bleed port, thereby alleviating a pressuregradient created during conditions (e.g., engine speeds and loads)exceeding a choke threshold. Additional flow is directed to the impellervia the second chamber and injection port. The technical effect of theadjusting the position of the movable sleeve, and hence flow through thecompressor, is to extend the range of engine operating conditions inwhich the compressor is able to operate stably and with high efficiency.

FIGS. 1-7B show example configurations with relative positioning of thevarious components. If shown directly contacting each other, or directlycoupled, then such elements may be referred to as directly contacting ordirectly coupled, respectively, at least in one example. Similarly,elements shown contiguous or adjacent to one another may be contiguousor adjacent to each other, respectively, at least in one example. As anexample, components laying in face-sharing contact with each other maybe referred to as in face-sharing contact. As another example, elementspositioned apart from each other with only a space there-between and noother components may be referred to as such, in at least one example. Asyet another example, elements shown above/below one another, at oppositesides to one another, or to the left/right of one another may bereferred to as such, relative to one another. Further, as shown in thefigures, a topmost element or point of element may be referred to as a“top” of the component and a bottommost element or point of the elementmay be referred to as a “bottom” of the component, in at least oneexample. As used herein, top/bottom, upper/lower, above/below, may berelative to a vertical axis of the figures and used to describepositioning of elements of the figures relative to one another. As such,elements shown above other elements are positioned vertically above theother elements, in one example. As yet another example, shapes of theelements depicted within the figures may be referred to as having thoseshapes (e.g., such as being circular, straight, planar, curved, rounded,chamfered, angled, or the like). Further, elements shown intersectingone another may be referred to as intersecting elements or intersectingone another, in at least one example. Further still, an element shownwithin another element or shown outside of another element may bereferred as such, in one example.

As one embodiment, a method includes flowing intake air in a firstdirection through a casing to an impeller of a compressor; selectivelyflowing intake air from the casing through a first chamber in anopposite, second direction, the first chamber circumferentiallysurrounding the casing; and selectively flowing intake air in the firstdirection through a second chamber to the impeller, the second chambercircumferentially surrounding the first chamber. In a first example ofthe method, the casing circumferentially surrounds at least part of theimpeller, and wherein selectively flowing intake air from the casingthrough the first chamber comprises selectively flowing intake air fromthe casing to the first chamber via a bleed port of the casing. A secondexample of the method optionally includes the first example and furtherincludes wherein selectively flowing intake air in the first directionthrough the second chamber to the impeller comprises selectively flowingintake air in the first direction through the second chamber to theimpeller via an injection port of the casing. A third example of themethod optionally includes one or more of the first and second examples,and further includes, wherein selectively flowing intake air from thecasing through the first chamber via the bleed port comprises actuatinga movable sleeve to a first position based on a mass air flow throughthe casing being below a threshold mass air flow, wherein while themovable sleeve is in the first position, the bleed port is open to thefirst chamber. A fourth example of the method optionally includes one ormore of the first through third examples, and further includes, whereinselectively flowing intake air in the first direction through the secondchamber to the impeller via the injection port comprises actuating themovable sleeve to a second position based on a mass air flow through thecasing being above a threshold mass air flow, wherein while the movablesleeve is in the second position, the injection port is open to thesecond chamber.

As another embodiment, a compressor includes an impeller rotatable abouta central axis and housed in a compressor housing; a casing at leastpartially surrounding the impeller, the casing including an injectionport and a bleed port; and a movable sleeve circumferentiallysurrounding the casing and defining a first air flow chamber between anouter surface of the casing and an inner surface of the movable sleeveand a second air flow chamber between an outer surface of the movablesleeve and an inner surface of the housing, the movable sleeveconfigured to selectively block and unblock the injection port and thebleed port. In a first example of the compressor, the casing forms aninner channel fluidically coupling an inlet of the compressor to theimpeller, and the bleed port fluidically couples the inner channel tothe first air flow chamber and the injection port fluidically couplesthe inner channel to the second air flow chamber. A second example ofthe compressor optionally includes the first example and furtherincludes wherein each of the first air flow chamber and the second airflow chamber are fluidically coupled to the inlet of the compressor. Athird example of the compressor optionally includes one or more of thefirst and second examples, and further includes, wherein the movablesleeve is adjustable to a first position where the bleed port is openand the injection port is blocked, fluidically coupling the innerchannel to the first air flow chamber such that intake air in the innerchannel flows through bleed port and to the first air flow chamber. Afourth example of the compressor optionally includes one or more of thefirst through third examples, and further includes, wherein the movablesleeve is adjustable to a second position where the bleed port isblocked and the injection port is open, fluidically coupling the innerchannel to the second air flow chamber such that intake air in thesecond air flow chamber flows through the injection port and to theimpeller. A fifth example of the compressor optionally includes one ormore of the first through fourth examples, and further includes, whereinthe bleed port is located upstream of the injection port in an intakeair flow direction through the compressor. A sixth example of thecompressor optionally includes one or more of the first through fifthexamples, and further includes support ribs coupled to the movablesleeve and projecting into the first air flow chamber. A seventh exampleof the compressor optionally includes one or more of the first throughsixth examples, and further includes, wherein the movable sleeveincludes an inwardly-curving downstream end and wherein theinwardly-curving downstream end includes a face configured to be inface-sharing contact with an outer surface of the casing. An eighthexample of the compressor optionally includes one or more of the firstthrough seventh examples, and further includes, wherein the face of theinwardly-curving downstream end is sized to block flow through eitherthe bleed port or the injection port. A ninth example of the compressoroptionally includes one or more of the first through eighth examples,and further includes, the movable sleeve including an inwardly-curvingupstream end and the inwardly-curving upstream end restricts air flowingin the first air flow chamber and directs it toward the impeller.

As another embodiment, a system includes a compressor, comprising: ahousing; an impeller housed within the housing and rotatable about acentral axis; a casing at least partially surrounding the impeller andan forming an inner channel fluidically coupling an inlet of thecompressor to the impeller, the casing including an injection port and ableed port; a movable sleeve circumferentially surrounding the casing; afirst air flow chamber extending along an outer surface of the casing;and a second air flow chamber extending along an outer surface of themovable sleeve; an actuating mechanism coupled to the movable sleeve;and a controller storing instructions executable to: actuate theactuating mechanism to move the movable sleeve to a first position wherethe bleed port is open to the first flow chamber and the injection portis blocked responsive to compressor operation in a surge region; andactuate the actuating mechanism to move the movable sleeve to a secondposition where the bleed port is blocked and the injection port is opento the second air flow chamber responsive to compressor operation in achoke region. In a first example of the system, the actuating mechanismincludes a linkage coupling a motor to the movable sleeve, wherein themotor is positioned outside the housing and the linkage traversesthrough the housing. A second example of the system optionally includesthe first example and further includes wherein the bleed port ispositioned in the casing upstream of the injection port in an intake airflow direction through the inner channel. A third example of the methodoptionally includes one or more of the first and second examples, andfurther includes wherein the injection port is positioned in the casingat a low-pressure region such that intake air in the second chamberflows through the injection port and to the impeller when the movablesleeve is in the second position. A fourth example of the methodoptionally includes one or more of the first through third examples, andfurther includes wherein the bleed port is positioned in the casing at ahigher-pressure region such that intake air in the inner channel flowsthrough the bleed port and to the first chamber when the movable sleeveis in the first position.

Note that the example control and estimation routines included hereincan be used with various engine and/or vehicle system configurations.The control methods and routines disclosed herein may be stored asexecutable instructions in non-transitory memory and may be carried outby the control system including the controller in combination with thevarious sensors, actuators, and other engine hardware. The specificroutines described herein may represent one or more of any number ofprocessing strategies such as event-driven, interrupt-driven,multi-tasking, multi-threading, and the like. As such, various actions,operations, and/or functions illustrated may be performed in thesequence illustrated, in parallel, or in some cases omitted. Likewise,the order of processing is not necessarily required to achieve thefeatures and advantages of the example embodiments described herein, butis provided for ease of illustration and description. One or more of theillustrated actions, operations and/or functions may be repeatedlyperformed depending on the particular strategy being used. Further, thedescribed actions, operations and/or functions may graphically representcode to be programmed into non-transitory memory of the computerreadable storage medium in the engine control system, where thedescribed actions are carried out by executing the instructions in asystem including the various engine hardware components in combinationwith the electronic controller.

It will be appreciated that the configurations and routines disclosedherein are exemplary in nature, and that these specific embodiments arenot to be considered in a limiting sense, because numerous variationsare possible. For example, the above technology can be applied to V-6,I-4, I-6, V-12, opposed 4, and other engine types. The subject matter ofthe present disclosure includes all novel and non-obvious combinationsand sub-combinations of the various systems and configurations, andother features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

1. A method, comprising: flowing intake air in a first direction througha casing to an impeller of a compressor; selectively flowing intake airfrom the casing through a first chamber in an opposite, seconddirection, the first chamber circumferentially surrounding the casing;and selectively flowing intake air in the first direction through asecond chamber to the impeller, the second chamber circumferentiallysurrounding the first chamber.
 2. The method of claim 1, wherein thecasing circumferentially surrounds at least part of the impeller, andwherein selectively flowing intake air from the casing through the firstchamber comprises selectively flowing intake air from the casing to thefirst chamber via a bleed port of the casing.
 3. The method of claim 2,wherein selectively flowing intake air in the first direction throughthe second chamber to the impeller comprises selectively flowing intakeair in the first direction through the second chamber to the impellervia an injection port of the casing.
 4. The method of claim 3, whereinselectively flowing intake air from the casing through the first chambervia the bleed port comprises actuating a movable sleeve to a firstposition based on a mass air flow through the casing being below athreshold mass air flow, wherein while the movable sleeve is in thefirst position, the bleed port is open to the first chamber.
 5. Themethod of claim 3, wherein selectively flowing intake air in the firstdirection through the second chamber to the impeller via the injectionport comprises actuating the movable sleeve to a second position basedon a mass air flow through the casing being above a threshold mass airflow, wherein while the movable sleeve is in the second position, theinjection port is open to the second chamber.
 6. A compressor,comprising: an impeller rotatable about a central axis and housed in acompressor housing; a casing at least partially surrounding theimpeller, the casing including an injection port and a bleed port; and amovable sleeve circumferentially surrounding the casing and defining afirst air flow chamber between an outer surface of the casing and aninner surface of the movable sleeve and a second air flow chamberbetween an outer surface of the movable sleeve and an inner surface ofthe housing, the movable sleeve configured to selectively block andunblock the injection port and the bleed port.
 7. The compressor ofclaim 6, wherein the casing forms an inner channel fluidically couplingan inlet of the compressor to the impeller, and wherein the bleed portfluidically couples the inner channel to the first air flow chamber andthe injection port fluidically couples the inner channel to the secondair flow chamber.
 8. The compressor of claim 7, wherein each of thefirst air flow chamber and the second air flow chamber are fluidicallycoupled to the inlet of the compressor.
 9. The compressor of claim 7,wherein the movable sleeve is adjustable to a first position where thebleed port is open and the injection port is blocked, fluidicallycoupling the inner channel to the first air flow chamber such thatintake air in the inner channel flows through bleed port and to thefirst air flow chamber.
 10. The compressor of claim 7, wherein themovable sleeve is adjustable to a second position where the bleed portis blocked and the injection port is open, fluidically coupling theinner channel to the second air flow chamber such that intake air in thesecond air flow chamber flows through the injection port and to theimpeller.
 11. The compressor of claim 6, wherein the bleed port islocated upstream of the injection port in an intake air flow directionthrough the compressor.
 12. The compressor of claim 6, furthercomprising support ribs coupled to the movable sleeve and projectinginto the first air flow chamber.
 13. The compressor of claim 6, whereinthe movable sleeve includes an inwardly-curving downstream end andwherein the inwardly-curving downstream end includes a face configuredto be in face-sharing contact with an outer surface of the casing. 14.The compressor of claim 13, wherein the face of the inwardly-curvingdownstream end is sized to block flow through either the bleed port orthe injection port.
 15. The compressor of claim 6, wherein the movablesleeve includes an inwardly-curving upstream end and wherein theinwardly-curving upstream end restricts air flowing in the first airflow chamber and directs it toward the impeller.
 16. A system,comprising: a compressor, comprising: a housing; an impeller housedwithin the housing and rotatable about a central axis; a casing at leastpartially surrounding the impeller and an forming an inner channelfluidically coupling an inlet of the compressor to the impeller, thecasing including an injection port and a bleed port; a movable sleevecircumferentially surrounding the casing; a first air flow chamberextending along an outer surface of the casing; and a second air flowchamber extending along an outer surface of the movable sleeve; anactuating mechanism coupled to the movable sleeve; and a controllerstoring instructions executable to: actuate the actuating mechanism tomove the movable sleeve to a first position where the bleed port is opento the first flow chamber and the injection port is blocked responsiveto compressor operation in a surge region; and actuate the actuatingmechanism to move the movable sleeve to a second position where thebleed port is blocked and the injection port is open to the second airflow chamber responsive to compressor operation in a choke region. 17.The system of claim 16, wherein the actuating mechanism includes alinkage coupling a motor to the movable sleeve, wherein the motor ispositioned outside the housing and the linkage traverses through thehousing.
 18. The system of claim 16, wherein the bleed port ispositioned in the casing upstream of the injection port in an intake airflow direction through the inner channel.
 19. The system of claim 18,wherein the injection port is positioned in the casing at a low-pressureregion such that intake air in the second chamber flows through theinjection port and to the impeller when the movable sleeve is in thesecond position.
 20. The system of claim 19, wherein the bleed port ispositioned in the casing at a higher-pressure region such that intakeair in the inner channel flows through the bleed port and to the firstchamber when the movable sleeve is in the first position.